Shoe structure

ABSTRACT

An open-toed shoe structure having a flexible sole having a predetermined shape; an engagement strap for the foot of a user, the engagement strap having a central part and two strap ends connected by two respective anchor points at two side edges opposite to the flexible sole; the engagement strap being configured in such a way that a user can put the foot under, so that the foot can be arranged between the sole and the engagement strap, wherein the engagement strap extends between the anchor points at the side edges and has a length between the strap ends substantially the same as the distance between the anchor points on the sole when the sole is in a planar arrangement without the foot, in order to move from a planar arrangement of the strap substantially parallel to the sole, to a raised arrangement of the central part of the strap with respect to the sole by the introduction of the foot.

FIELD OF THE INVENTION

The present invention relates to a light open-toed sandal-type shoe.

In particular, the invention relates to a structure of such a shoe for use at swimming pools, hotels, wellness centers, on a journey, etc.

DESCRIPTION OF THE PRIOR ART

Many common methods are known to make light open-toed shoes.

For example, US2004000070A1 proposes to die-cut a flexible lamina, in order to determine a shaped sole that can be bent on itself to form an arch in which to put the foot P like flip flops.

It is desirable to provide a shoe that, even if made as die-cut of leather or synthetic material, like the above cited document, is stronger and long-lasting, as well as provides comfort and stability to the foot P of the user.

A shoe also exists with plane shape having an upper that is flattened on the sole when the foot is not present, as described in FR2904919. The upper is made of a resilient material in such a way that, by the introduction of the foot, it stretches up to a length suitable for containing the foot. Such solution imposes a trade-off between elasticity and lengthening, to avoid of either choking the foot or leaving the foot too free, to attempt giving stability and safety to the gait.

This solution is not suitable for open-toed shoes, which can be used like a sandal, since the elasticity of the upper would render instable the foot during the gait.

SUMMARY OF THE INVENTION

It is therefore a feature of the present invention to provide a shoe structure that meets such needs.

It is also a feature of the present invention to provide an open-toed shoe that is light and of minimum encumbrance for easy transportation.

It is another feature of the present invention to provide an open-toed shoe that provides comfort and stability during the gait, for example at swimming pools, in hotels and wellness centers, on a journey, for example on an airplane, on a boat, etc.

This and other objects are achieved by a shoe structure comprising:

-   -   a flexible sole having a predetermined shape;     -   at least one engagement strap for engagement of the foot of a         user, said at least one engagement strap comprising a central         part and two ends connected by two respective anchor points at         two opposite side edges of said flexible sole, said or each         engagement strap being configured in such a way that a user can         put the foot under, so that the foot can be arranged between the         sole and the engagement strap,     -   wherein said engagement strap extends between said anchor points         at said side edges and has a length between said ends         substantially the same as the distance between said anchor         points determined on said sole when said sole is in a planar         arrangement without said foot, in order to move from a planar         arrangement of said strap substantially parallel to said sole,         to a raised arrangement of said central part of said strap with         respect to said sole by the introduction of the foot,     -   wherein said engagement strap and said sole are configured so         that, with the introduction of the foot of the user between said         engagement strap and said sole, said engagement strap pulls said         side edges of said sole without that said engagement strap         substantially is lengthened, and said sole, by the pulling         action of said side edges by said strap, causes said side edges         to bend assuming a “half pipe” like configuration that wraps         partially the foot increasing the comfort.

This way, the side edges of the sole, which bend by the pulling action of the strap, give an extremely comfortable wrapping effect to the sole.

Furthermore, since the sole is flexible, it adapts to the foot giving the sensation of a gait similar to that with naked feet, and also giving good grip to the ground, minimizing the risks of slipping, for example on board of swimming pools, on a boat, etc.

Since the engagement strap has the same length as the distance between two anchor points it causes the strap to level with the sole when not used, causing the sole to be very flat, like a “sole fish”, with minimum encumbrance, for example in a suitcase or in sports bag used when going to the swimming pool.

In a possible exemplary embodiment, said sole has a predetermined length and a predetermined transversal maximum width, determined at said anchor points, and the ratio between said length and said transversal maximum width is less than or equal to 2.3, preferably less than or equal to 2, so that said side edges protrude laterally with respect to the part of the sole which actually supports the foot and by the pulling action of said side edges by said strap cause said half-pipe like shape. This way, with respect to a shoe that normally has a ratio between sole length and width between the strap anchor points about 3, in this exemplary embodiment of the invention the side edges protrude laterally with respect to the foot sole in a remarkable way, allowing their appropriate bending with wrapping effect on the foot, by the pulling action of the engagement strap.

In a possible exemplary embodiment, said sole has thickness set between 2-6 mm, preferably between 3-5 mm, in order to assist the side edges to bend by the pulling action of said strap in the presence of the foot. A thinner sole, between a half and one third of a normal flip-flop type sandal or similar, makes it possible an easy bending and an adhesion to the foot, in order to have a sensation of gait like with naked feet, with the sole that partially follows the plantar arch, and avoids a flat shape with risk of slipping, for example with wet ground like around swimming pools, on a boat, etc.

In a possible exemplary embodiment, said strap is anchored to said sole by a junction selected from the group consisting of: seaming, welding, gluing, integral. The various anchoring techniques lets the strap of being as far as possible level with the sole without the foot.

In a possible exemplary embodiment, said sole has a shape substantially “leaf-like”, with small width in a rear zone configured to receive the heel of the foot, a central portion of maximum width at the or each strap, and a front portion of width less than the central portion, but larger than the rear portion. Such shape allows the central zone of the sole, at the or each strap, to bend and wrap partially the foot.

This shoe can be made from a flexible lamina is an easy and quick way since it can be die-cut from a single flexible flat sheet.

In a possible exemplary embodiment, said sole comprises

-   -   a first flexible lamina having said predetermined shape;     -   a second flexible lamina overlapped and glued to said first         flexible lamina,     -   said second flexible lamina having a plurality of cuts arranged         to define said strap for engagement of the foot with said two         ends at said anchor points at the two opposite side edges of         said second flexible lamina, said engagement strap being free         from said first flexible lamina and configured to move from a         planar arrangement laying on the same plane of said second         flexible lamina, to a raised arrangement, in which said central         part is raised with respect to said second flexible lamina and         pulls said side edges, causing said first and said second         flexible lamina to assume said “half pipe” like configuration

This way, the or each strap, when the shoe is not used, is arranged level with the second flexible lamina. In fact, the or each engagement strap that has the same length as the distance between two anchor points causes the strap to flatten back onto the sole when not used, and lays down within the second flexible lamina, causing the sole to be very flat, like a “sole fish”, with minimum encumbrance.

Furthermore, the addition of the first flexible lamina mediates the direct contact with the ground, resulting a more comfortable and hygienic shoe. Furthermore, the two sheets can be made of two different materials, for example the lower lamina of EVA and the upper lamina of TPU. Other configurations can provide both the flexible laminas of TPU. Alternatively, one or both laminas can be made of leather or rubber for shoes.

In a possible exemplary embodiment, said second flexible lamina has a top plan shape identical to said first flexible lamina. This way, the boundary of both flexible laminas can be made with a single die-cut operation.

In a possible exemplary embodiment, said cuts end with holes, in particular circular, for discharging stresses at the ends of said cuts, for reducing the intensification of stresses at said ends and to stop any propagation said cuts. This way, it is avoided that wearing actions trigger the formation of a tear that could reduce drastically the useful life of the object.

Advantageously, a plurality is provided of engagement straps, each engagement strap of said plurality defined by a couple of cuts, said plurality of engagement straps comprising:

-   -   a proximal engagement strap substantially orthogonal to a         longitudinal axis of said shoe structure, said proximal         engagement strap arranged to overlap to the instep of the foot         of the user;     -   at least one distal engagement strap, said distal engagement         strap arranged to overlap, in use, to at least one finger of the         foot.

In a possible exemplary embodiment, a first distal engagement strap and a second distal engagement strap are provided, said first distal engagement strap and said second distal engagement strap being at an angle with respect to said longitudinal axis according to angles of opposite sign, the strap ends present between said first distal engagement strap and said second distal engagement strap acting as Y support between the first and second toes of the foot of the user.

In an alternative embodiment, a proximal engagement strap and a distal engagement strap can be provided, said proximal engagement strap housing all the toes of the foot. Such solution makes it possible, for example, the use of the shoe wearing normal socks.

In a possible exemplary embodiment, said distal engagement strap is anchored to said sole in an intermediate position by a Y strap portion allowing an agile ab-adduction movement of the first and second toes.

In a possible exemplary embodiment, an engagement strap defined by three cuts is provided, said engagement strap is adapted to overlap to the instep and to the toes of the foot of the user, the portion of said engagement strap between two distal cuts acting as Y support between the first and second toes of the foot of the user.

According to another aspect of the invention, a method for construction of a shoe structure, according to anyone of the embodiments above defined, comprises the steps of:

-   -   forming said first and said second flexible lamina;     -   gluing said second flexible lamina to said first flexible         lamina, overlapping the external shapes;     -   wherein, upstream of the step of gluing, a step is provided of         die-cutting said second flexible lamina     -   said second flexible lamina having a plurality of cuts arranged         to define at least one strap for engagement of the foot of a         user, said at least one engagement strap comprising a central         part and two ends at two opposite side edges of said second         flexible lamina,     -   and during said step of gluing said engagement straps are         separated from the laying plane of said second flexible lamina,         so that said engagement straps turn out not glued with respect         to said first flexible lamina, in order to pass, in use, from a         planar arrangement laying on the same plane of said second         flexible lamina, to a raised arrangement, in which said central         part is raised with respect to said second flexible lamina.

Advantageously, said step of gluing is made prearranging a plane template between said engagement straps and said second flexible lamina, so that an application of glue on said second flexible lamina opposite to said plane template prevents the distribution of glue on said engagement straps.

According to another aspect of the invention, a die-cutter structure for construction of a shoe structure as above defined, comprises a plurality of removable knives arranged to make said cuts on said second flexible lamina for defining said engagement straps for the foot, said removable knives of said plurality being in variable number and according to the number of engagement straps that are to be to provide on said second flexible lamina, and being connected to the die-cutter through a connection means, in particular bolts, said connection means being releasable for the removal and/or the change of said removable knives, and making it possible the use of a same die-cutter to provide selectively a variety of types of cuts on said second flexible lamina.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be now shown with the following description of an embodiment thereof, exemplifying but not limitative, with reference to the attached drawings in which:

FIGS. 1-2 show a first exemplary embodiment of the shoe structure, according to the invention respectively with presence or absence of the foot of a user;

FIG. 2 a shows the shoe of FIGS. 1, 2 compared to a flip-flop sandal of the prior art of identical length;

FIGS. 3 a-3B show an elevational front view of the exemplary embodiment of FIG. 1, respectively, in the raised arrangement and in the planar arrangement;

FIG. 4 shows an exemplary embodiment of the shoe according to the invention;

FIG. 5 shows an exemplary embodiment of the shoe of FIG. 4 with an exemplary embodiment of the sole made in two layers;

FIG. 6 between the shoe of FIG. 5 in an exploded view with the two layers distinct from each other;

FIG. 7 shows a top plan view of an exemplary embodiment of the shoe of FIGS. 4, 5 with holes for discharging stresses at the anchor points of the engagement straps;

FIGS. 8, 9 show an elevational side view and a front view of the upper lamina of the shoe of FIGS. 5, 6;

FIG. 10 shows in exploded perspective view a further exemplary embodiment of the shoe structure, according to the invention, where in the upper lamina two engagement straps are made;

FIGS. 11, 12, 13 show the first flexible lamina of an exemplary embodiment of FIG. 10, according to three views, respectively, from the above, lateral and from behind;

FIG. 14 shows in a perspective view another exemplary embodiment of the shoe structure, according to the invention, where in the first flexible lamina a single engagement strap is made;

FIGS. 15, 16 show the first flexible lamina of an exemplary embodiment of FIG. 14, according to two different views, respectively, from the above and lateral;

FIG. 17 shows in a perspective view still another exemplary embodiment of the shoe structure, according to the invention, where the engagement strap is in a position more advanced and at an angle with larger width at the inside of the foot;

FIGS. 18, 19 show the first flexible lamina of FIG. 17 according to two different views, respectively, from the above and lateral;

FIG. 20 shows in a perspective view another structure of the exemplary embodiment of FIG. 14, wherein a single engagement strap is defined by three cuts instead of two;

FIGS. 21, 22 show the first flexible lamina of FIG. 20, according to two different views, respectively, from the above and lateral;

FIG. 23 shows in a perspective view a further exemplary embodiment of the shoe of FIG. 7, where the three engagement straps have through holes;

FIG. 24 shows a further exemplary embodiment of the shoe of FIG. 7, with two engagement straps and an intermediate portion of the front engagement strap to provide the Y support;

FIG. 24 a shows a top plan view of the shoe of FIG. 24 compared with a conventional flip-flop sandal of corresponding length;

FIG. 25 shows the step of die-cutting of the first flexible lamina, by a die-cut operation;

FIG. 26 shows the step of gluing the first flexible lamina.

DESCRIPTION OF A PREFERRED EXEMPLARY EMBODIMENT

With reference to FIGS. 1, 2, a possible exemplary embodiment of a shoe structure 10, according to the invention, comprises:

-   -   a flexible sole 30 having a predetermined shape;     -   an engagement strap 20, for the foot P of a user, with a central         part 25 and two strap ends 26, which are connected by two         respective anchor points 50′ at two opposite side edges 50 to         flexible sole 30.

The engagement strap 20 is configured in such a way that a user can put the foot P under it, so that the foot can be arranged between sole 30 and engagement strap 20.

According to the invention, the engagement strap 20 extends between the anchor points 50′ of the side edges 50 for a distance between strap ends 26 substantially the same as the distance between the anchor points 50′ determined on sole 30 when sole 30 is in a planar arrangement without foot P.

This way, by the introduction of the foot P, the shoe 10 turns from a planar arrangement of the sole, where strap 20 is substantially parallel to sole 30, to a raised arrangement of the central part 25 of strap 20 with respect to sole 30.

In the raised position, by the force applied to the strap by the introduction of foot P, the side edges 50 move up, in such a way that sole 30 assume a half-pipe like shape that wraps partially the foot P of the user increasing the comfort. In particular, strap 20 is configured so that, with the introduction of the foot, it pulls the side edges 50 of the sole without substantially lengthening, and sole 30, by the pulling action at side edges 50, bend assuming such half-pipe like shape that wraps partially the foot increasing the comfort.

In particular, sole 30 may have a predetermined length L and a predetermined maximum transversal width I, determined at the height of the anchor points 50′, in such a way that the ratio between the length L and the maximum transversal width I is less than or equal to 2.3, preferably less than or equal to 2.

With reference to FIG. 2 a, with respect to a normal shoe, where this ratio is normally between 2.7 and 3, and even more, in the shoe according to the invention the side edges have a much larger lateral exceeding edge with respect to the foot P, in such a way that strap 20 causes sole 30 to assume the half-pipe shape and the side edges 50 wrap partially the foot P increasing the comfort.

FIGS. 3 a-3B show an elevational front view of an exemplary embodiment of FIG. 1, respectively, in the raised arrangement and in the planar arrangement. As shown, the thickness t of the shoe 100 according to the invention is much thinner with respect to the slippers of the prior art, in order to assist the deformation during the introduction of the foot. In particular, the thickness t is less than 8 mm, preferably between 2-6 mm, advantageously between 3-5 mm, for example 4 mm. In addition to assisting the side edges to bend by the pulling action of strap 20 in the presence of the foot, such a tjin sole 30, between the a half and one third less than a normal flip-flop type sandal or similar, makes it possible an easy bending and an adhesion to the foot, in order to have a sensation of gait like with naked feet, with sole that partially follows the plantar arch, and avoids a flat shape with risk of slipping, for example with wet ground like around swimming pools, on a boat, etc.

Strap 20 can be connected to sole 30 by seaming, welding, gluing, or integral.

As shown in FIG. 4, the sole has a substantially “leaf-like” shape, with smaller width in a rear zone for receiving the heel of the foot, a central portion of maximum width at the straps 20, 21, 22, and a front portion of width larger than the rear portion. Such shape allows the central zone of the sole, at the anchor points the straps 20, 21, 22, to bend and wrap partially the foot P. The front straps 22, 21 form a Y support for the first and second toes, with three fastening portions to sole 30.

A possible embodiment of the strap “integral” is the solution of FIGS. 5, 6, which is particularly advantageous because with sole completely flat the straps 120, 121, 122, when the shoe is not used, are arranged level with the sole.

More in detail, in FIGS. 5, 6, a shoe structure 100 is shown, according to the invention, comprising a first flexible lamina 110 having a predetermined shape, in particular a curvilinear shape wider than a sole of a traditional shoe, with “leaf-like” shape like that of FIG. 4, and a second flexible lamina 130. The latter, in use, is overlapped and glued to the first flexible lamina 110.

As shown in FIG. 6, in a specific embodiment of the invention, the second lamina 130 has a shape equal to the first lamina 110.

Still with reference to FIGS. 5, 6, in the second flexible lamina 130 by die-cuts 115 are made, in particular three couples of cuts 115, which define a respective engagement strap 120, 121, 122 for each couple, in particular a proximal engagement strap 120, a first distal engagement strap 121 and a second distal engagement strap 122.

Such engagement straps 120, 121, 122 are configured for being raised from the plane where the second flexible lamina 130 lays, and are used for engaging the foot P of a user with the shoe structure 100. In particular, each engagement strap 120, 121, 122 comprises a central part 125, which can be raised from the plane of the second lamina 130, and two side ends 126, which pull the side edges 50 of the second flexible lamina 130.

The straps 120, 121, 122 are configured so that, with the introduction of the foot they pull the side edges 50 of the sole without lengthening the straps, and sole 30, by the pulling action of the side edges 50, bends assuming a half-pipe like shape that wraps partially the foot increasing the comfort.

As shown in FIGS. 5, 6, at the side ends 126 of the engagement straps 120, 121, 122, the side edges 50 protrude outwards than the profile of the flexible laminas 110, 130.

With reference to FIG. 7, the proximal engagement strap 120 is substantially orthogonal to a longitudinal axis 10 of the shoe structure 100, and is configured for overlapping to the instep of the foot P of the user. The distal engagement straps 121, 122 are, instead, at predetermined angles with respect to the longitudinal axis 10. In particular, the angles of the engagement straps 121, 122 have opposite signs with respect to axis 10, and have absolute values in a range between 30° and 70°. Such feature allows the straps 121, 122 to receive respectively four toes of the foot and the first toe.

More in detail, in the exemplary embodiment of FIG. 7, the first distal engagement strap 122 is overlapped to the first toe of foot P, whereas the second distal engagement strap 121 is overlapped to the other four fingers. This way, the ends 126 present between the engagement strap 121 and the engagement strap 122 act as Y support between the first and second toes of the foot P of the user.

This structure with holes for discharging stresses is used also, as advantageous exemplary embodiment, to the shoe of FIG. 4, with sole 30 made in a single layer;

FIG. 7 shows furthermore, the presence of circular holes 40 for discharging stresses at the ends of the cuts 115, for reducing the intensification of stresses on such ends and avoid an easy propagation of tears starting from the cuts 115 same.

Always as also shown in FIG. 7, and possibly in all the exemplary embodiments of the invention, the sole 130 may have a predetermined length L and a predetermined maximum transversal width I, determined at the height of the anchor points 50′, in such a way that the ratio between the length L and the maximum transversal width I is less than or equal to 2.3, preferably less than 2, also here exceeding outwardly from the foot P, in such a way that also here the straps 120, 121, 122 cause the sole 130 to assume a half pipe like shape by the side edges 50 which wrap the foot P increasing the comfort.

FIGS. 8, 9, still concerning an exemplary embodiment of FIGS. 5-7, show the configuration of the shoe when the user puts the foot, not shown, below the engagement straps 120, 121, 122, which are raised, and the second flexible lamina 130 loses its natural shape substantially planar and acquires a half-pipe like shape, where the ends 50 move up, wrap partially the foot P of the user and increase the comfort. In this case, the zone of the side edges 50 that protrude outwards at the side ends 126 assists the bending. In the presence of the first flexible lamina 110 to it glued, the two sheets would bend in a similar way.

With reference to FIGS. 10-13, an exemplary embodiment of the shoe structure 100, according to the invention, differs from FIGS. 5-9 for the fact of providing two engagement straps 120, 123, instead of three.

In this exemplary embodiment, with reference to FIG. 11, the engagement strap 123, like the engagement strap 120, is substantially perpendicular to the longitudinal axis 10, and is adapted to overlap both to first toe and the other four toes of the foot P of the user.

With reference to FIGS. 14-16, a further exemplary embodiment of the shoe structure 100, according to the invention, differs from that of FIG. 5-9 and from that of FIG. 10-13 for the fact of providing a single engagement strap 120, in a position substantially central or antero-central with respect to the longitudinal extension of the shoe structure 100, like straps 20, 120 of the previous Figures. In this exemplary embodiment, the engagement strap 120 is overlapped to the instep of the foot P in proximal position with respect to the joint between foot P and ankle.

With reference to FIGS. 17-19, a further exemplary embodiment differs from the exemplary embodiment of FIG. 14 since the engagement strap 120 is in a position more advanced with respect to the longitudinal extension of the shoe structure 100 and would overlap to the instep of the foot P in an intermediate position between the joint between the ankle and the toes. Furthermore, in this exemplary embodiment, the cuts 115 that define the engagement strap 120 do not have direction parallel to each other, so that distal cuts 115 follows more accurately the toes of the foot P.

With reference to FIGS. 20-22, a further exemplary embodiment is shown that differs from an exemplary embodiment of FIG. 14 since the engagement strap 120 is defined by a proximal cut 115 a, a first distal cut 115 b and a second distal cut 115 c. In this exemplary embodiment, the portion 120 is overlapped to a portion of the foot P larger than the previous exemplary embodiments, and substantially extends from the joint between ankle and foot P up to the first phalanxes of the toes. This way, the portion of engagement strap 120 between the two distal cuts 115 b, 115 c works as Y support between the first toe and the second toe of the foot P of the user.

With reference to FIG. 23, an alternative embodiment of that of FIG. 5, and which can applied also to the other figures, provides that on the engagement straps 120, 121, 122 holes 45 are made that allow a higher transpiration of the foot P at the engagement straps same.

Obviously, the shape of the engagement straps 120, 121, 122, 123 can be customized according to the model of shoe, and also can be different concerning the layout of the cuts and for anatomical reasons of the user.

FIG. 24 shows a further exemplary embodiment of the top plan of the shoe with respect FIG. 7, where two engagement straps 120, 123 are provided and an elongated extension 123 a in the front engagement strap 123 to provide the Y support for the first two toes.

FIG. 24 a shows a top plan view of the shoe of FIG. 24 compared with a conventional flip-flop sandal of corresponding length. It is shown that, under a same length L, with respect to the width I of the sandal according to the invention, the sandal of traditional type has a much lower width, determined at the anchor points side of the uppers. As already shown in the previous examples, this allows the shoe according to the invention of bending up to the half-pipe configuration in the presence of the foot and to wrap partially the foot.

In FIG. 25 a phase of the construction process of the shoe structure 100 is shown, and more in detail the step of die-cutting.

The die-cutter 200 has a plurality of removable knives 215 arranged to provide the cuts 115, by compression, actuated by a press 250, against the second flexible lamina 130 by removable knives 215.

At the ends end of such removable knives 215 cylindrical punches 216 are arranged to provide the circular holes for discharging stresses 40, at the ends of the cuts 115.

Removable knives 215 are connected to the die-cutter 200 through a connection means, in particular bolts, 240, which allow its removal and/or the change, making it possible the use of a same die-cutter 200 to provide a variety of types of cuts 115 on the second flexible lamina 130.

The die-cutter 200 is also provided with a further blade 216 at its own outer perimeter, which allows forming the first and the second flexible lamina 110, 130;

FIG. 26 shows the second flexible lamina 130 during the step of gluing, and, in particular during the step of distributing the glue. Once the die-cut operation has generated the engagement straps 120, 121, 122, it is necessary to distribute the glue on all the surface of the second flexible lamina 130, except from the engagement straps 120, 121, 122.

This way, it is possible to glue the second flexible lamina 130 to the first flexible lamina 110, allowing that the engagement straps 120, 121, 122 are kept raised.

So, during the distribution of the glue, a plane template 20 is arranged, of plastics, cardboard or other material, between the engagement straps 120, 121, 122 and the second flexible lamina 130.

The foregoing description exemplary specific embodiments will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such embodiment without further research and without parting from the invention, and, accordingly, it is meant that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation. 

1. An open-toed shoe structure (10, 100) comprising: a flexible sole (30) having a predetermined shape; at least one engagement strap (20, 21, 22, 23, 120, 121, 122, 123) for a foot (P) of a user, said at least one engagement strap comprising a central part (25) and two strap ends (26) connected by two respective anchor points (50′) at two side edges (50) opposite to said flexible sole, said or each engagement strap being configured in such a way that a user can put the foot (P) under, so that the foot can be arranged between the sole and the engagement strap, wherein said engagement strap extends between said anchor points at said side edges and has a length between said strap ends (26) substantially the same as the distance between said anchor points (50′) determined on said sole (30) when said sole is in a planar arrangement without said foot (P), in order to move from a planar arrangement of said strap substantially parallel to said sole, to a raised arrangement of said central part (25, 125) of said strap with respect to said sole (30) by the introduction of the foot (P), characterized in that said engagement strap and said sole are configured so that, with the introduction of the foot (P) of the user between said engagement strap and said sole, said engagement strap pulls said side edges (50) of said sole without that said engagement strap substantially is lengthened, and said sole (30), by the pulling action of said side edges (50) by said strap, causes said side edges to bend (50) assuming a half-pipe like shape that wraps partially the foot (P) increasing the comfort.
 2. Shoe structure (100), according to claim 1, wherein said sole has a predetermined length (L) and a predetermined transversal maximum width (1), determined at said anchor points (50′), where the ratio between said length and said transversal maximum width is less than or equal to 2.3, preferably less than or equal to 2, so that said side edges protrude laterally with respect to the part of the sole which actually supports the foot and by the pulling action of said side edges (50) by said strap determines said half-pipe like shape.
 3. Shoe structure (100), according to claim 1, wherein said sole (30) has thickness set between 2-6 mm, preferably between 3-5 mm, in order to assist the side edges to bend by the pulling action of said strap in the presence of the foot.
 4. Shoe structure (100), according to claim 1, wherein said strap is anchored to said sole by a junction selected from the group consisting of: seaming, welding, gluing, integral.
 5. Shoe structure (100), according to claim 1, wherein said sole has a shape substantially “leaf-like”, with small width in a rear zone configured to receive the heel of the foot, a central portion of maximum width at the or each strap, and a front portion of width less than said central portion but larger than the rear portion.
 6. Shoe structure (100), according to claim 1, wherein said sole (30) comprises a first flexible lamina (110) having said predetermined shape; a second flexible lamina (130) overlapped and glued to said first flexible lamina (110), said second flexible lamina (130) having a plurality of cuts (115) arranged to define said engagement strap (120, 121, 122, 123) for the foot (P) with said two ends (126) at said anchor points at the two side edges (50) opposite to said second flexible lamina (130), said engagement strap (120,121,122,123) being free from said first flexible lamina (110) and configured to move from a planar arrangement laying on the same plane of said second flexible lamina (130), to a raised arrangement, in which said central part (125) is raised with respect to said second flexible lamina (130) and pulls said side edges (50), causing said first (110) and said second (130) flexible lamina to achieve said “half pipe” like configuration.
 7. Shoe structure (100), according to claim 6, wherein said second flexible lamina (130) has a top plan shape identical to said first flexible lamina (110).
 8. Shoe structure (100), according to claim 6, wherein said cuts (115) end with holes, in particular circular, for discharging stresses (40) at the ends of said cuts (115), for reducing the intensification of stresses on said ends and to stop a propagation of said cuts (115).
 9. Shoe structure (100), according to claim 1, wherein a plurality of engagement straps (120,121,122,123) is provided, each engagement strap (120,121,122,123) of said plurality defined by a couple of cuts (115), said plurality of engagement straps (120,121,122,123) comprising: a proximal engagement strap (120) substantially orthogonal to a longitudinal axis (10) of said shoe structure (100), said proximal engagement strap (120) arranged to overlap to the instep of the foot (P) of the user; at least one distal engagement strap (121,122, 123), said distal engagement strap (121,122, 123) arranged to overlap, in use, at least one finger of the foot (P).
 10. Shoe structure (100), according to claim 9, wherein a first distal engagement strap (121) and a second distal engagement strap (122) are provided, said first distal engagement strap (121) and said second distal engagement strap (122) being at an angle with respect to said longitudinal axis (10) according to angles of opposite sign, the end (126) present between said first distal engagement strap (121) and said second distal engagement strap (122) acting as Y support between the first and second toes of the foot (P) of the user.
 11. Shoe structure (100), according to claim 8, wherein a proximal engagement strap (120) and a distal engagement strap (123) are provided, said proximal engagement strap arranged to house all the toes of the foot (P).
 12. Shoe structure (100), according to claim 10, wherein said distal engagement strap (123) is anchored to said sole in an intermediate position by a Y strap portion (123 a).
 13. Shoe structure (100), according to claim 8, wherein an engagement strap (120) is provided defined by three cuts (115 a,115)b, (115)c), said engagement strap (120) arranged to overlap to the instep and to the toes of the foot (P) of the user, the portion of said engagement strap (120) between two distal cuts (115 b, 115 c) acting as Y support between the first and second toes of the foot (P) of the user.
 14. A method for construction of a shoe structure (100), according to claim 6, said method comprising the steps of: forming said first (110) and said second (130) flexible lamina; gluing said second flexible lamina (130) to said first flexible lamina (110), overlapping the external shapes; characterized in that it comprises, upstream of the step of gluing, a step of die-cutting of said second flexible lamina (130) said second flexible lamina (130) having a plurality of cuts (115) arranged to define at least one engagement strap (120,121,122,123) for the foot (P) of a user, said at least one engagement strap (120,121,122,123) comprising a central part (125) and two ends (126) at two side edges (50) opposite to said second flexible lamina (130), and in that during said step of gluing said engagement straps (120,121,122,123) are separated from the laying plane of said second flexible lamina (130), so that said engagement straps (120,121,122,123) turn out not glued with respect to said first flexible lamina, in order to pass, in use, from a planar arrangement laying on the same plane of said second flexible lamina (130), to a raised arrangement, in which said central part (125) is raised with respect to said second flexible lamina (130).
 15. Method according to claim 14, wherein said step of gluing is made prearranging a plane template (20) between said engagement straps (120,121,122,123) and said second flexible lamina (130), so that an application of glue on said second flexible lamina (130) opposite to said plane template (20) prevents the distribution of glue on said engagement straps (120,121,122,123).
 16. A die-cutter structure for construction of a shoe structure (100), according to claim 6, said die-cutter (200) comprising a plurality of removable knives (215) arranged to make said cuts (115) on said second flexible lamina (130) for defining said engagement straps (120,121,122,123) for the foot (P), said removable knives (215) of said plurality being in variable number and according to the number of engagement straps (120,121,122,123) that are to be to provide on said second flexible lamina (130), and being connected to the die-cutter (200) by connection means (240), in particular bolts, said connection means (240) being releasable for the removal and/or the change of said removable knives (215), and for making it possible the use of the same die-cutter (200) to provide a variety of types of cuts (115) on said second flexible lamina (130). 